Cell of Cosmarium botrytis. Notice pyramidal shape of the semicells and firmly lined cell wall evenly beset with fine granules.

Cell dimensions (L x B): ca 70 x 55 µm



Desmid of the month
September 2013

Cosmarium botrytis

C. botrytis is a frequently recorded, medium sized, granulate Cosmarium species that may be readily confused with similarly shaped species. Semicells are about pyramidal in outline. An important feature to watch is the cell wall which (in optical cross section) is firmly lined in C. botrytis, slightly undulate or crenate in many resembling species. In the Netherlands, C. botrytis is widely distributed in various types of slightly acidic, mesotrophic water bodies. Zygospores are incidentally encountered.

Cell of C. botrytis showing pattern of granules on frontral surface.

Cosmarium botrytis, zygosporeImage © Marien van Westen

Zygospore of C. botrytis

Zygospore of Cosmarium botrytis in more detail.Image © Koos Meesters

Zygospore of C. botrytis in more detail. Notice furcate spines.

SEM image of C. botrytis, detail showing cell wall pores.

SEM image of C. botrytis